Charles Xavier cannot find any mental trace of his stepbrother, Cain Marko, draining his energy using Cerebro to do so. He tells Storm he would know if Cain had died, but he has completely disappeared. A group of X-Men go to search for him.
They end up on the Ultraverse Earth and see anyone who allies themselves with Juggernaut and Sienna Blaze as their enemies.
Amber Hunt tries to rip through the dimensional barriers to send the Earth-616 characters home, but Fireworms that draw energy off of swallowing them keep them from crossing the barrier. The x-Men are not affected by whatever this is, and Iceman is able to get them out of the Fireworm's gullet unharmed.
Forced to return without the Juggernaut, they are at least able to report to Professor Xavier that Cain has formed a protective bond with Amber Hunt and believe he may eventually arrive back on their Earth a changed man.